Shielded electrical cable

ABSTRACT

A shielded electrical cable ( 1802 ) includes a conductor set ( 1804 ), two generally parallel shielding films ( 1808 ) disposed around the conductor set ( 1804 ), and a transition portion ( 1834 ) defined by the shielding films  1808  and the conductor set ( 1804 ). The conductor set ( 1804 ) includes one or more substantially parallel longitudinal insulated conductors ( 1806 ). The shielding films ( 1808 ) include a concentric portion ( 1808′ ) substantially concentric with at least one of the conductors ( 1806 ) and a parallel portion ( 1808″ ) wherein the shielding films ( 1808 ) are substantially parallel. The transition portion ( 1834 ) provides a gradual transition between the concentric portion ( 1808′ ) and the parallel portion ( 1808″ ) of the shielding films ( 1808 ).

Cross Reference to Related Applications

This application is a national stage filing under 35 U.S.C. 371 ofPCT/US2010/038930, filed 17 Jun. 2010, which claims priority to U.S.Application No. 61/218,739, filed 19 Jun. 2009; U.S. Application No.61/260,881, filed 13 Nov. 2009; U.S. Application No. 61/348,800, filed27 May 2010; and U.S. Application No. 61/352,473, filed 08 Jun. 2010,the disclosures of which are incorporated by reference in their entiretyherein.

TECHNICAL FIELD

The present disclosure relates generally to shielded electrical cablesfor the transmission of electrical signals. In particular, the presentinvention relates to shielded electrical cables that can bemass-terminated and provide high speed electrical properties.

BACKGROUND

Electrical cables for transmission of electrical signals are well known.One common type of electrical cable is a coaxial cable. Coaxial cablesgenerally include an electrically conductive wire surrounded by aninsulator. The wire and insulator are surrounded by a shield, and thewire, insulator, and shield are surrounded by a jacket. Another commontype of electrical cable is a shielded electrical cable comprising oneor more insulated signal conductors surrounded by a shielding layerformed, for example, by a metal foil. To facilitate electricalconnection of the shielding layer, a further un-insulated conductor issometimes provided between the shielding layer and the insulation of thesignal conductor or conductors. Both these common types of electricalcable normally require the use of specifically designed connectors fortermination and are often not suitable for the use of mass-terminationtechniques, i.e., the simultaneous connection of a plurality ofconductors to individual contact elements, such as, e.g., electricalcontacts of an electrical connector or contact elements on a printedcircuit board. Although electrical cables have been developed tofacilitate these mass-termination techniques, these cables often havelimitations in the ability to mass-produce them, in the ability toprepare their termination ends, in their flexibility, and in theirelectrical performance. In view of the advancements in high speedelectrical and electronic components, a continuing need exists forelectrical cables that are capable of transmitting high speed signals,facilitate mass-termination techniques, are cost-effective, and can beused in a large number of applications.

SUMMARY

In one aspect, the present invention provides a shielded electricalcable including a conductor set, two generally parallel shielding filmsdisposed around the conductor set, and a transition portion defined bythe shielding films and the conductor set. The conductor set includesone or more substantially parallel longitudinal insulated conductors.The shielding films include a concentric portion substantiallyconcentric with at least one of the conductors and a parallel portionwherein the shielding films are substantially parallel. The transitionportion provides a gradual transition between the concentric portion andthe parallel portion of the shielding films.

In another aspect, the present invention provides a shielded electricalcable including a plurality of spaced apart conductor sets arrangedgenerally in a single plane, two generally parallel shielding filmsdisposed around the conductor sets, and a plurality of transitionportions defined by the shielding films and the conductor sets. Eachconductor set includes one or more substantially parallel longitudinalinsulated conductors. The shielding films include a plurality ofconcentric portions substantially concentric with at least one of theconductors and a plurality of parallel portions wherein the shieldingfilms are substantially parallel. The transition portions provide agradual transition between the concentric portions and the parallelportions of the shielding films.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. The Figures and detailed description that follow below moreparticularly exemplify illustrative embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention.

FIGS. 2 a-2 e are front cross-sectional views of five other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIG. 3 is a perspective view of two shielded electrical cables of FIG. 1terminated to a printed circuit board.

FIGS. 4 a-4 d are top views of an exemplary termination process of ashielded electrical cable according to an aspect of the presentinvention.

FIG. 5 is a top view of another exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention.

FIG. 6 is a top view of another exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention.

FIGS. 7 a-7 d are front cross-sectional views of four other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIGS. 8 a-8 c are front cross-sectional views of three other exemplaryembodiments of a shielded electrical cable according to aspects of thepresent invention.

FIGS. 9 a-9 b are top and partially cross-sectional front views,respectively, of an exemplary embodiment of an electrical assemblyaccording to an aspect of the present invention terminated to a printedcircuit board.

FIGS. 10 a-10 e and 10 f-10 g are perspective and front cross-sectionalviews, respectively, illustrating an exemplary method of making ashielded electrical cable according to an aspect of the presentinvention.

FIGS. 11 a-11 c are front cross-sectional views illustrating a detail ofan exemplary method of making a shielded electrical cable according toan aspect of the present invention.

FIGS. 12 a-12 b are a front cross-sectional view of another exemplaryembodiment of a shielded electrical cable according to an aspect of thepresent invention and a corresponding detail view, respectively.

FIGS. 13 a-13 b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable according to an aspect of thepresent invention.

FIGS. 14 a-14 b are front cross-sectional views of two other exemplaryembodiments of a shielded electrical cable according to an aspect of thepresent invention.

DETAILED DESCRIPTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof.The accompanying drawings show, by way of illustration, specificembodiments in which the invention may be practiced. It is to beunderstood that other embodiments may be utilized, and structural orlogical changes may be made without departing from the scope of thepresent invention. The following detailed description, therefore, is notto be taken in a limiting sense, and the scope of the invention isdefined by the appended claims.

Referring now to the Figures, FIG. 1 illustrates an exemplary embodimentof a shielded electrical cable according to an aspect of the presentinvention. Shielded electrical cable 2 includes a plurality of spacedapart conductor sets 4 arranged generally in a single plane. Eachconductor set includes two substantially parallel longitudinal insulatedconductors 6. Insulated conductors 6 may include insulated signal wires,insulated power wires, or insulated ground wires. Two generally parallelshielding films 8 are disposed around conductor sets 4. A conformableadhesive layer 10 is disposed between shielding films 8 and bondsshielding films 8 to each other on both sides of each conductor set 4.In one embodiment, conductor sets 4 have a substantially curvilinearcross-sectional shape, and shielding films 8 are disposed aroundconductor sets 4 such as to substantially conform to and maintain thecross-sectional shape. Maintaining the cross-sectional shape maintainsthe electrical characteristics of conductor sets 4 as intended in thedesign of conductor sets 4. This is an advantage over some conventionalshielded electrical cables where disposing a conductive shield around aconductor set changes the cross-sectional shape of the conductor set.

Although in the embodiment illustrated in FIG. 1, each conductor set 4includes two insulated conductors 6, in other embodiments, eachconductor set 4 may include one or more insulated conductors 6. Forexample, instead of shielded electrical cable 2 including four conductorsets 4 each including two insulated conductors 6 as shown in FIG. 1,shielded electrical cable 2 may include one conductor set 4 includingeight insulated conductors 6, or eight conductor sets 4 each includingone insulated conductor 6. This flexibility in arrangements of conductorsets 4 and insulated conductors 6 allows shielded electrical cable 2 tobe configured suitable for the intended application. For example,conductor sets 4 and insulated conductors 6 may be configured to form amultiple twinaxial cable, i.e., multiple conductor sets 4 each includingtwo insulated conductors 6, a multiple coaxial cable, i.e., multipleconductor sets each including one insulated conductor 6, or acombination thereof. In other embodiments, a conductor set 4 may furtherinclude a conductive shield (not shown) disposed around the one or moreinsulated conductors 6, and an insulative jacket (not shown) disposedaround the conductive shield.

In the embodiment illustrated in FIG. 1, shielded electrical cable 2further includes optional longitudinal ground conductors 12. Groundconductors 12 may include ground wires or drain wires. Ground conductors12 are spaced apart from and extend in substantially the same directionas insulated conductors 6. Conductor sets 4 and ground conductors 12 arearranged generally in a single plane. Shielding films 8 are disposedaround ground conductors 12 and conformable adhesive layer 10 bondsshielding films 8 to each other on both sides of ground conductors 12.Ground conductors 12 may electrically contact at least one of shieldingfilms 8.

FIGS. 2 a-2 e illustrate various exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS. 2a-2 e are specifically intended to illustrate various examples ofarrangements of conductors disposed between two shielding films.

Referring to FIG. 2 a, shielded electrical cable 102 includes a singleconductor set 104. Conductor set 104 includes a single longitudinalinsulated conductor 106. Two generally parallel shielding films 108 aredisposed around conductor set 104. A conformable adhesive layer 110 isdisposed between shielding films 108 and bonds shielding films 108 toeach other on both sides of conductor set 104. Shielded electrical cable102 further includes optional longitudinal ground conductors 112. Groundconductors 112 are spaced apart from and extend in substantially thesame direction as insulated conductor 106. Conductor set 104 and groundconductors 112 are arranged generally in a single plane. Shielding films108 are disposed around ground conductors 112 and conformable adhesivelayer 110 bonds shielding films 108 to each other on both sides ofground conductors 112. Ground conductors 112 may electrically contact atleast one of shielding films 108. Insulated conductor 106 is effectivelyarranged in a coaxial or single ended cable arrangement.

Referring to FIG. 2 b, shielded electrical cable 202 is similar toshielded electrical cable 102 illustrated in FIG. 2 a. Where shieldedelectrical cable 102 includes a single conductor set 104 including asingle longitudinal insulated conductor 106, shielded electrical cable202 includes a single conductor set 204 including two substantiallyparallel longitudinal insulated conductors 206. Insulated conductors 206are arranged generally in a single plane and effectively in a twinaxialor differential pair cable arrangement.

Referring to FIG. 2 c, shielded electrical cable 302 is similar toshielded electrical cable 102 illustrated in FIG. 2 a. Where shieldedelectrical cable 102 includes a single conductor set 104 including asingle longitudinal insulated conductor 106, shielded electrical cable302 includes a single conductor set 304 including two longitudinalinsulated conductors 306. Insulated conductors 306 are arrangedeffectively in a twisted pair cable arrangement, whereby insulatedconductors 306 twist around each other in longitudinal direction.

Referring to FIG. 2 d, shielded electrical cable 402 is similar toshielded electrical cable 102 illustrated in FIG. 2 a. Where shieldedelectrical cable 102 includes a single conductor set 104 including asingle longitudinal insulated conductor 106, shielded electrical cable402 includes a single conductor set 404 including four longitudinalinsulated conductors 406. Insulated conductors 406 are arrangedeffectively in a quad cable arrangement, whereby insulated conductors406 may twist around each other in longitudinal direction, or may besubstantially parallel.

Referring back to FIGS. 2 a-2 d, further embodiments of shieldedelectrical cables according to aspects of the present invention mayinclude a plurality of spaced apart conductor sets 104, 204, 304 or 404,or combinations thereof, arranged generally in a single plane.Optionally, the shielded electrical cables may include a plurality ofground conductors 112 spaced apart from and extending generally in thesame direction as the insulated conductors of the conductor sets,wherein the conductor sets and ground conductors are arranged generallyin a single plane. FIG. 2 e illustrates an exemplary embodiment of sucha shielded electrical cable.

Referring to FIG. 2 e, shielded electrical cable 502 includes aplurality of spaced apart conductor sets 104, 204 arranged generally ina single plane. Shielded electrical cable 502 further includes optionalground conductors 112 disposed between conductor sets 104, 204 and atboth ends of shielded electrical cable 502. Two generally parallelshielding films 508 are disposed around conductor sets 104, 204 andground conductors 112. A conformable adhesive layer 510 is disposedbetween shielding films 508 and bonds shielding films 508 to each otheron both sides of each conductor set 104, 204 and each ground conductor.Shielded electrical cable 502 includes a combination of coaxial cablearrangements (conductor sets 104) and a twinaxial cable arrangement(conductor set 204) and may therefore be referred to as a hybrid cablearrangement.

FIG. 3 illustrates two shielded electrical cables 2 terminated to aprinted circuit board 14. Because insulated conductors 6 and groundconductors 12 are arranged generally in a single plane, shieldedelectrical cables 2 are well suited for mass-stripping, i.e., thesimultaneous stripping of shielding films 8 and insulated conductors 6,and mass-termination, i.e., the simultaneous terminating of the strippedends of insulated conductors 6 and ground conductors 12, which allows amore automated cable assembly process. This is an advantage of theshielded electrical cables according to aspects of the presentinvention. In FIG. 3, the stripped ends of insulated conductors 6 andground conductors 12 are terminated to contact elements 16 on printedcircuit board 14. In other embodiments, the stripped ends of insulatedconductors 6 and ground conductors 12 may be terminated to any suitableindividual contact elements of any suitable termination point, such as,e.g., electrical contacts of an electrical connector.

FIGS. 4 a-4 d illustrate an exemplary termination process of shieldedelectrical cable 2 to printed circuit board 14. This termination processcan be a mass-termination process and includes the steps of stripping(illustrated in FIGS. 4 a-4 b), aligning (illustrated in FIG. 4 c), andterminating (illustrated in FIG. 4 d). When forming shielded electricalcable 2, the arrangement of conductor sets 4, insulated conductors 6,and ground conductors 12 of shielded electrical cable 2 may be matchedto the arrangement of contact elements 16 on printed circuit board 14,which would eliminate any significant manipulation of the end portionsof shielded electrical cable 2 during alignment or termination.

In the step illustrated in FIG. 4 a, an end portion 8 a of shieldingfilms 8 is removed. Any suitable method may be used, such as, e.g.,mechanical stripping or laser stripping. This step exposes an endportion of insulated conductors 6 and ground conductors 12. In oneaspect, mass-stripping of end portion 8 a of shielding films 8 ispossible because they form an integrally connected layer that isseparate from the insulation of insulated conductors 6. Removingshielding films 8 from insulated conductors 6 allows protection againstelectrical shorting at these locations and also provides independentmovement of the exposed end portions of insulated conductors 6 andground conductors 12. In the step illustrated in FIG. 4 b, an endportion 6 a of the insulation of insulated conductors 6 is removed. Anysuitable method may be used, such as, e.g., mechanical stripping orlaser stripping. This step exposes an end portion of the conductor ofinsulated conductors 6. In the step illustrated in FIG. 4 c, shieldedelectrical cable 2 is aligned with printed circuit board 14 such thatthe end portions of the conductors of insulated conductors 6 and the endportions of ground conductors 12 of shielded electrical cable 2 arealigned with contact elements 16 on printed circuit board 14. In thestep illustrated in FIG. 4 d, the end portions of the conductors ofinsulated conductors 6 and the end portions of ground conductors 12 ofshielded electrical cable 2 are terminated to contact elements 16 onprinted circuit board 14. Examples of suitable termination methods thatmay be used include soldering, welding, crimping, mechanical clamping,and adhesively bonding, to name a few.

FIG. 5 illustrates another exemplary embodiment of a shielded electricalcable according to an aspect of the present invention. Shieldedelectrical cable 602 is similar to shielded electrical cable 2illustrated in FIG. 1. In addition, shielded electrical cable 602includes a plurality of longitudinal splits 18 disposed betweenconductor sets 4. Splits 18 separate individual conductor sets 4 atleast along a portion of the length of shielded electrical cable 602,thereby increasing at least the lateral flexibility of shieldedelectrical cable 602. This allows shielded electrical cable 602 to beplaced more easily into a curvilinear outer jacket, e.g. In otherembodiments, splits 18 may be placed such as to separate individual ormultiple conductor sets 4 and ground conductors 12. To maintain thespacing of conductor sets 4 and ground conductors 12, splits 18 may bediscontinuous along the length of shielded electrical cable 602. Tomaintain the spacing of conductor sets 4 and ground conductors 12 in atleast one end portion A of shielded electrical cable 602 and therebymaintaining mass-termination capability, splits 18 may not extend intoone or both end portions A. Splits 18 may be formed in shieldedelectrical cable 602 using any suitable method, such as, e.g., lasercutting or punching. Instead of or in combination with longitudinalsplits, other suitable shapes of openings may be formed in shieldedelectrical cable 602, such as, e.g., holes, e.g., to increase at leastthe lateral flexibility of shielded electrical cable 602.

FIG. 6 illustrates another exemplary embodiment of a shielded electricalcable according to an aspect of the present invention. Shieldedelectrical cable 702 is similar to shielded electrical cable 602illustrated in FIG. 5. Effectively, in shielded electrical cable 702,one of conductor sets 4 is replaced by two ground conductors 12.Shielded electrical cable 702 includes longitudinal splits 18 and 18′.Split 18 separates individual conductor sets 4 along a portion of thelength of shielded electrical cable 702 and does not extend into endportions A of shielded electrical cable 702. Split 18′ separatesindividual conductor sets 4 along the length of shielded electricalcable 702 and extends into end portions A of shielded electrical cable702, which effectively splits shielded electrical cable 702 into twoindividual shielded electrical cables 702′, 702″. Shielding films 8 andground conductors 12 provide an uninterrupted ground plane in each ofthe individual shielded electrical cables 702′, 702″. This exemplaryembodiment illustrates the advantage of the parallel processingcapability of the shielded electrical cables according to aspects of thepresent invention, whereby multiple shielded electrical cables may beformed simultaneously.

FIGS. 7 a-7 d illustrate four other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS. 7a-7 e are specifically intended to illustrate various examples ofconstructions of the shielding films of the shielded electrical cables.In one aspect, at least one of the shielding films may include aconductive layer and a non-conductive polymeric layer. The conductivelayer may include any suitable conductive material, including but notlimited to copper, silver, aluminum, gold, and alloys thereof. Thenon-conductive polymeric layer may include any suitable polymericmaterial, including but not limited to polyester, polyimide,polyamide-imide, polytetrafluoroethylene, polypropylene, polyethylene,polyphenylene sulfide, polyethylene naphthalate, polycarbonate, siliconerubber, ethylene propylene diene rubber, polyurethane, acrylates,silicones, natural rubber, epoxies, and synthetic rubber adhesive. Thenon-conductive polymeric layer may include one or more additives and/orfillers to provide properties suitable for the intended application. Inanother aspect, at least one of the shielding films may include alaminating adhesive layer disposed between the conductive layer and thenon-conductive polymeric layer. In another aspect, at least one of theshielding films may include a stand-alone conductive film. Theconstruction of the shielding films may be selected based on a number ofdesign parameters suitable for the intended application, such as, e.g.,flexibility, electrical performance, and configuration of the shieldedelectrical cable (such as, e.g., presence and location of groundconductors). In one embodiment, the shielding films include anintegrally formed shielding film. In one embodiment, the shielding filmshave a thickness in the range of 0.01 mm to 0.05 mm. The shielding filmsprovide isolation, shielding, and precise spacing between the conductorsets, and enable a more automated and lower cost cable manufacturingprocess. In addition, the shielding films prevent a phenomenon known as“signal suck-out” or resonance, whereby high signal attenuation occursat a particular frequency range. This phenomenon typically occurs inconventional shielded electrical cables where a conductive shield iswrapped around a conductor set.

Referring to FIG. 7 a, shielded electrical cable 802 includes a singleconductor set 804. Conductor set 804 includes two substantially parallellongitudinal insulated conductors 806. Two generally parallel shieldingfilms 808 are disposed around conductor set 804. Shielding films 808include a conformable adhesive layer 810 that bonds shielding films 808to each other on both sides of conductor set 804. Insulated conductors806 are arranged generally in a single plane and effectively in atwinaxial or differential pair cable arrangement. Shielding films 808include a conductive layer 808 a and a non-conductive polymeric layer808 b. Non-conductive polymeric layer 808 b faces insulated conductors806. Conductive layer 808 a may be deposited onto non-conductivepolymeric layer 808 b using any suitable method.

Referring to FIG. 7 b, shielded electrical cable 902 includes a singleconductor set 904. Conductor set 904 includes two substantially parallellongitudinal insulated conductors 906. Two generally parallel shieldingfilms 908 are disposed around conductor set 904. Shielding films 908include a conformable adhesive layer 910 that bonds shielding films 908to each other on both sides of conductor set 904. Insulated conductors906 are arranged generally in a single plane and effectively in atwinaxial or differential pair cable arrangement. Shielding films 908include a conductive layer 908 a and a non-conductive polymeric layer908 b. Conductive layer 908 a faces insulated conductors 906. Conductivelayer 908 a may be deposited onto non-conductive polymeric layer 908 busing any suitable method.

Referring to FIG. 7 c, shielded electrical cable 1002 includes a singleconductor set 1004. Conductor set 1004 includes two substantiallyparallel longitudinal insulated conductors 1006. Two generally parallelshielding films 1008 are disposed around conductor set 1004. Shieldingfilms 1008 include a conformable adhesive layer 1010 that bondsshielding films 1008 to each other on both sides of conductor set 1004.Insulated conductors 1006 are arranged generally in a single plane andeffectively in a twinaxial or differential pair cable arrangement.Shielding films 1008 include a stand-alone conductive film.

Referring to FIG. 7 d, shielded electrical cable 1102 includes a singleconductor set 1104. Conductor set 1104 includes two substantiallyparallel longitudinal insulated conductors 1106. Two generally parallelshielding films 1108 are disposed around conductor set 1104. Shieldingfilms 1108 include a conformable adhesive layer 1110 that bondsshielding films 1108 to each other on both sides of conductor set 1104.Insulated conductors 1106 are arranged generally in a single plane andeffectively in a twinaxial or differential pair cable arrangement.Shielding films 1108 include a conductive layer 1108 a, a non-conductivepolymeric layer 1108 b, and a laminating adhesive layer 1108 c disposedbetween conductive layer 1108 a and non-conductive polymeric layer 1108b, thereby laminating conductive layer 1108 a to non-conductivepolymeric layer 1108 b. Conductive layer 1108 a faces insulatedconductors 1106.

Referring back to FIG. 1, conformable adhesive layer 10 of shieldedelectrical cable 2 is disposed between shielding films 8 and bondsshielding films 8 to each other on both sides of each conductor set 4.In one embodiment, conformable adhesive layer 10 may be disposed on oneof shielding films 8. In another embodiment, conformable adhesive layer10 may be disposed on both shielding films 8. Conformable adhesive layer10 may include an insulative adhesive and provide an insulative bondbetween shielding films 8. Optionally, conformable adhesive layer 10 mayprovide an insulative bond between at least one of shielding films 8 andinsulated conductors 6, and between at least one of shielding films 8and ground conductors 12. Conformable adhesive layer 10 may include aconductive adhesive and provide a conductive bond between shieldingfilms 8. Optionally, conformable adhesive layer 10 may provide aconductive bond between at least one of shielding films 8 and groundconductors 12. Suitable conductive adhesives include conductiveparticles to provide the flow of electrical current. The conductiveparticles can be any of the types of particles currently used, such asspheres, flakes, rods, cubes, amorphous, or other particle shapes. Theymay be solid or substantially solid particles such as carbon black,carbon fibers, nickel spheres, nickel coated copper spheres,metal-coated oxides, metal-coated polymer fibers, or other similarconductive particles. These conductive particles can be made fromelectrically insulating materials that are plated or coated with aconductive material such as silver, aluminum, nickel, or indiumtin-oxide. The metal-coated insulating material can be substantiallyhollow particles such as hollow glass spheres, or may comprise solidmaterials such as glass beads or metal oxides. The conductive particlesmay be on the order of several tens of microns to nanometer sizedmaterials such as carbon nanotubes. Suitable conductive adhesives mayalso include a conductive polymeric matrix. In one aspect, conformableadhesive layer 10 may include a continuous adhesive layer extendingalong the entire length and width of shielding films 8. In anotheraspect, conformable adhesive layer 10 may include a discontinuousadhesive layer. For example, conformable adhesive layer 10 may bepresent only in some portions along the length or width of shieldingfilms 8. In one embodiment, discontinuous adhesive layer 10 includes aplurality of longitudinal adhesive stripes that are disposed, e.g., onboth sides of each conductor set 4 and ground conductors 12. In oneembodiment, conformable adhesive layer 10 includes at least one of apressure sensitive adhesive, a hot melt adhesive, a thermoset adhesive,and a curable adhesive. In one embodiment, conformable adhesive layer 10is configured to provide a bond between shielding films 8 that issubstantially stronger than a bond between one or more insulatedconductor 6 and shielding films 8. This may be achieved, e.g., byselecting the adhesive formulation accordingly. An advantage of thisadhesive configuration is that shielding films 8 are readily strippablefrom the insulation of insulated conductors 6. In another embodiment,conformable adhesive layer 10 is configured to provide a bond betweenshielding films 8 and a bond between one or more insulated conductor 6and shielding films 8 that are substantially equally strong. Anadvantage of this adhesive configuration is that insulated conductors 6are anchored between shielding films 8. On bending shielded electricalcable 2, this allows for little relative movement and therefore reducesthe likelihood of buckling of shielding films 8. Suitable bond strengthsmay be chosen based on the intended application. In one embodiment,conformable adhesive layer 10 has a thickness of less than about 0.13mm. In a preferred embodiment, conformable adhesive layer 10 has athickness of less than about 0.05 mm.

Conformable adhesive layer 10 may conform to achieve desired mechanicaland electrical performance characteristics of shielded electrical cable2. In one aspect, conformable adhesive layer 10 may conform to bethinner between shielding films 8 in areas between conductor sets 4,which increases at least the lateral flexibility of shielded electricalcable 2. This allows shielded electrical cable 2 to be placed moreeasily into a curvilinear outer jacket, e.g. In another aspect,conformable adhesive layer 10 may conform to be thicker in areasimmediately adjacent conductor sets 4 and substantially conform toconductor sets 4. This increases the mechanical strength and enablesforming a curvilinear shape of shielding films 8 in these areas, whichincreases the durability of shielded electrical cable 2, e.g., duringflexing of the cable. In addition, this helps to maintain the positionand spacing of insulated conductors 6 relative to shielding films 8along the length of shielded electrical cable 2, which results inuniform impedance and superior signal integrity of shielded electricalcable 2. In another aspect, conformable adhesive layer 10 may conform toeffectively be partially of completely removed between shielding films 8in areas between conductor sets 4. As a result, shielding films 8electrically contact each other in these areas, which increases theelectrical performance of shielded electrical cable 2. In anotheraspect, conformable adhesive layer 10 may conform to effectively bepartially of completely removed between at least one of shielding films8 and ground conductors 12. As a result, ground conductors 12electrically contact at least one of shielding films 8 in these areas,which increases the electrical performance of shielded electrical cable2. Even if a thin conformable adhesive layer 10 exists between at leastone of shielding films 8 and ground conductors 12, asperities on groundconductors 12 may break through conformable adhesive layer 10 toestablish electrical contact as intended.

FIGS. 8 a-8 c illustrate three other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention. FIGS. 8a-8 c are specifically intended to illustrate examples of the placementof ground conductors in the shielded electrical cables. An aspect of ashielded electrical cable is proper grounding of the shield. Shieldedelectrical cables according to aspects of the present invention can begrounded in a number of ways. In one aspect, the ground conductorselectrically contact at least one of the shielding films such thatgrounding the ground conductors also grounds the shielding films. Inthis arrangement, the ground conductors may also be referred to as“drain wires”. In another aspect, the ground conductors do notelectrically contact the shielding films, but are individual elements inthe cable construction that may be independently terminated to anysuitable individual contact element of any suitable termination point,such as, e.g., a contact element on a printed circuit board. In thisarrangement, the ground conductors may also be referred to as “groundwires”. FIG. 8 a illustrates an exemplary embodiment of a shieldedelectrical cable according to an aspect of the present invention whereinthe ground conductors are positioned external to the shielding films.FIGS. 8 b-8 c illustrate two exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention whereinthe ground conductors are positioned between the shielding films, andmay be included in the conductor set. One or more ground conductors maybe placed in any suitable position external to the shielding films,between the shielding films, or a combination of both.

Referring to FIG. 8 a, shielded electrical cable 1202 includes a singleconductor set 1204. Conductor set 1204 includes two substantiallyparallel longitudinal insulated conductors 1206. Two generally parallelshielding films 1208 are disposed around conductor set 1204. Aconformable adhesive layer 1210 is disposed between shielding films 1208and bonds shielding films 1208 to each other on both sides of conductorset 1204. Insulated conductors 1206 are arranged generally in a singleplane and effectively in a twinaxial or differential pair cablearrangement. Shielded electrical cable 1202 further includes a pluralityof ground conductors 1212 positioned external to shielding films 1208.Ground conductors 1212 are placed over, under, and on both sides ofconductor set 1204. Optionally, shielded electrical cable 1202 includesprotective films 1220 surrounding shielding films 1208 and groundconductors 1212. Protective films 1220 include a protective layer 1220 aand an adhesive layer 1220 b bonding protective layer 1220 a toshielding films 1208 and ground conductors 1212. Alternatively,shielding films 1208 and ground conductors 1212 may be surrounded by anouter conductive shield, such as, e.g., a conductive braid, and an outerinsulative jacket (not shown).

Referring to FIG. 8 b, shielded electrical cable 1302 includes a singleconductor set 1304. Conductor set 1304 includes two substantiallyparallel longitudinal insulated conductors 1306. Two generally parallelshielding films 1308 are disposed around conductor set 1304. Aconformable adhesive layer 1310 is disposed between shielding films 1308and bonds shielding films 1308 to each other on both sides of conductorset 1304. Insulated conductors 1306 are arranged generally in a singleplane and effectively in a twinaxial or differential pair cablearrangement. Shielded electrical cable 1302 further includes a pluralityof ground conductors 1312 positioned between shielding films 1308. Twoof the ground conductors 1312 are included in conductor set 1304, andtwo of the ground conductors 1312 are spaced apart from conductor set1304.

Referring to FIG. 8 c, shielded electrical cable 1402 includes a singleconductor set 1404. Conductor set 1404 includes two substantiallyparallel longitudinal insulated conductors 1406. Two generally parallelshielding films 1408 are disposed around conductor set 1404. Aconformable adhesive layer 1410 is disposed between shielding films 1408and bonds shielding films 1408 to each other on both sides of conductorset 1404. Insulated conductors 1406 are arranged generally in a singleplane and effectively in a twinaxial or differential pair cablearrangement. Shielded electrical cable 1402 further includes a pluralityof ground conductors 1412 positioned between shielding films 1408. Allof the ground conductors 1412 are included in conductor set 1404. Two ofthe ground conductors 1412 and insulated conductors 1406 are arrangedgenerally in a single plane.

FIGS. 9 a-9 b illustrate an exemplary embodiment of an electricalassembly according to an aspect of the present invention terminated to aprinted circuit board.

Electrical assembly 1500 includes a shielded electrical cable 1502 andan electrically conductive cable clip 1522. Shielded electrical cable1502 includes a plurality of spaced apart conductor sets 1504 arrangedgenerally in a single plane. Each conductor set includes twosubstantially parallel longitudinal insulated conductors 1506. Twogenerally parallel shielding films 1508 are disposed around conductorsets 1504. A conformable adhesive layer 1510 is disposed betweenshielding films 1508 and bonds shielding films 1508 to each other onboth sides of each conductor set 1504. Cable clip 1522 is clamped orotherwise attached to an end portion of shielded electrical cable 1502such that at least one of shielding films 1508 electrically contactscable clip 1522. Cable clip 1522 is configured for termination to aground reference, such as, e.g., contact element 1516 on printed circuitboard 1514, to establish a ground connection between shielded electricalcable 1502 and the ground reference. Cable clip may be terminated to theground reference using any suitable method, including soldering,welding, crimping, mechanical clamping, and adhesively bonding, to namea few. When terminated, cable clip 1522 may facilitate termination ofthe end portions of the conductors of insulated conductors 1506 ofshielded electrical cable 1502 to contact elements of a terminationpoint, such as, e.g., contact elements 16 on printed circuit board 14.Shielded electrical cable 1502 may include one or more ground conductorsas described herein that may electrically contact cable clip 1522 inaddition to or instead of at least one of shielding films 1508.

FIGS. 10 a-10 g illustrate an exemplary method of making a shieldedelectrical cable according to an aspect of the present invention.Specifically, FIGS. 10 a-10 g illustrate an exemplary method of makingshielded electrical cable 2 illustrated in FIG. 1.

In the step illustrated in FIG. 10 a, insulated conductors 6 are formedusing any suitable method, such as, e.g., extrusion. Insulatedconductors 6 may be formed of any suitable length. Insulated conductors6 may then be provided as such or cut to a desired length. Groundconductors 12 may be formed and provided in a similar fashion (notshown). In the step illustrated in FIG. 10 b, shielding films 8 areformed. A single layer or multilayer web may be formed using anysuitable method, such as, e.g., continuous wide web processing.Shielding films 8 may be formed of any suitable length. Shielding films8 may then be provided as such or cut to a desired length and/or width.Shielding films 8 may be pre-formed to have transverse partial folds toincrease flexibility in the longitudinal direction. As illustrated inFIG. 10 b, shielding films 8 include conformable adhesive layer 10,which may be formed on shielding films 8 using any suitable method, suchas, e.g., laminating or sputtering. In the step illustrated in FIG. 10c, a plurality of insulated conductors 6, ground conductors 12, andshielding films 8 are provided. A forming tool 24 is provided. Formingtool 24 includes a pair of forming rolls 26 a, 26 b having a shapecorresponding to a cross-sectional shape of shielded electrical cable 2and include a bite 28. Insulated conductors 6, ground conductors 12, andshielding films 8 are arranged according to the configuration ofshielded electrical cable 2, and positioned in proximity to formingrolls 26 a, 26 b, after which they are concurrently fed into bite 28 offorming rolls 26 a, 26 b and disposed between forming rolls 26 a, 26 b.Forming tool 24 forms shielding films 8 around conductor sets 4 andground conductor 12 and bonds shielding films 8 to each other on bothsides of each conductor set 4 and ground conductors 12. Heat may beapplied to facilitate bonding. Although in this embodiment, formingshielding films 8 around conductor sets 4 and ground conductor 12 andbonding shielding films 8 to each other on both sides of each conductorset 4 and ground conductors 12 occur in a single operation, in otherembodiments, these steps may occur in separate operations. FIG. 10 dillustrates shielded electrical cable 2 as it is formed by forming tool24. In the step illustrated in FIG. 10 e, longitudinal splits 18 areformed between conductor sets 4. Splits 18 may be formed in shieldedelectrical cable 2 using any suitable method, such as, e.g., lasercutting or punching. In the step illustrated in FIG. 10 f, shieldingfilms 8 of shielded electrical cable 2 are folded and an outerconductive shield 30 is provided around the folded shielding films 8using any suitable method. In the step illustrated in FIG. 10 g, anouter jacket 32 is provided around outer conductive shield 30 using anysuitable method, such as, e.g., extrusion. In other embodiments, outerconductive shield 30 may be omitted and outer jacket 32 may be providedaround the folded shielding films 8.

FIGS. 11 a-11 c illustrate a detail of an exemplary method of making ashielded electrical cable according to an aspect of the presentinvention. FIGS. 11 a-11 c are specifically intended to illustrate anexample of the conforming of conformable adhesive layers during theforming and bonding of shielding films.

In the step illustrated in FIG. 11 a, an insulated conductor 1606, aground conductor 1612 spaced apart from insulated conductor 1606, andtwo shielding films 1608 are provided. Shielding films 1608 each includea conformable adhesive layer 1610. In the steps illustrated in FIGS. 11b-11 c, shielding films 1608 are formed around insulated conductor 1606and ground conductor 1612 and bonded to each other. Initially, asillustrated in FIG. 11 b, conformable adhesive layers 1610 still havetheir original thickness. As the forming and bonding of shielding films1608 proceeds, conformable adhesive layers 1610 conform to achievedesired mechanical and electrical performance characteristics ofshielded electrical cable 1602. Specifically, as illustrated in FIG. 11c, conformable adhesive layers 1610 conform to be thinner betweenshielding films 1608 on both sides of insulated conductor 1606 andground conductor 1612; a portion of conformable adhesive layers 1610displaces away from these areas. Further, conformable adhesive layers1610 conform to be thicker in areas immediately adjacent insulatedconductor 1606 and ground conductor 1612, and substantially conform toinsulated conductor 1606 and ground conductor 1612; a portion ofconformable adhesive layers 1610 displaces into these areas. Further,conformable adhesive layers 1610 conform to effectively be removedbetween shielding films 1608 and ground conductor 1612; conformableadhesive layers 1610 displace away from these areas such that groundconductor 1612 electrically contacts shielding films 1608.

In certain exemplary embodiments, the shielded electrical cableaccording to an aspect of the present invention includes a transitionportion positioned on one or both sides of the conductor set. Thistransition portion is configured to provide high manufacturability andstrain and stress relief of the shielded electrical cable. Maintainingthis transition portion at a substantially constant configuration(including aspects such as, e.g., size, shape, and content) along thelength of the shielded electrical cable facilitates the shieldedelectrical cable to have substantially uniform electrical properties,such as, e.g., impedance, skew, insertion loss, reflection, modeconversion, eye opening, and jitter. Additionally, in certainembodiments, such as, e.g., embodiments wherein the conductor setincludes two substantially parallel longitudinal insulated conductorsarranged generally in a single plane and effectively in a twinaxial ordifferential pair cable arrangement, maintaining this transition portionat a substantially constant configuration along the length of theshielded electrical cable beneficially provides substantially the sameelectromagnetic field deviation from an ideal concentric case for bothconductors in the conductor set. Thus, careful control of theconfiguration of this transition portion along the length of theshielded electrical cable contributes to the electrical performance ofthe cable. FIGS. 12 a-14 b illustrate various exemplary embodiments of ashielded electrical cable according to aspects of the present inventionthat include a transition portion disposed on one or both sides of theconductor set.

Referring now to FIGS. 12 a-12 b, shielded electrical cable 1702includes a single conductor set 1704. Conductor set 1704 includes asingle longitudinal insulated conductor 1706. Two generally parallelshielding films 1708 are disposed around conductor set 1704. An optionalconformable adhesive layer 1710 is disposed between shielding films 1708and bonds shielding films 1708 to each other on both sides of conductorset 1704. Insulated conductor 1706 is effectively arranged in a coaxialor single ended cable arrangement. Shielding films 1708 include aconductive layer 1708 a and a non-conductive polymeric layer 1708 b.Conductive layer 1708 a faces insulated conductors 1706. Thisconfiguration of shielding films 1708 is similar to the configuration ofshielding films 908 shown in FIG. 7 b. Alternatively, the configurationof shielding films 1708 may be similar to the configuration of shieldingfilms 808 shown in FIG. 7 a, shielding films 1008 shown in FIG. 7 c, orshielding films 1108 shown in FIG. 7 d, for example. Shielding films1708 include a concentric portion 1708′ substantially concentric withconductor 1706 and parallel portions 1708″ wherein shielding films 1708are substantially parallel. In other embodiments, shielding films 1708may include a single parallel portion 1708″. Shielded electrical cable1702 further includes transition portions 1734 positioned on both sidesof conductor set 1704. In other embodiments, shielded electrical cable1702 may include a transition portion 1734 positioned on only one sideof conductor set 1704. Transition portions 1734 are defined by shieldingfilms 1708 and conductor set 1704 and provide a gradual transitionbetween concentric portion 1708′ and parallel portion 1708″ of shieldingfilms 1708. As opposed to a sharp transition, such as, e.g., aright-angle transition or a transition point (as opposed to a transitionportion), a gradual transition, such as, e.g., a substantially sigmoidaltransition, provides strain and stress relief for shielding films 1708in transition portions 1734 and prevents damage to shielding films 1708when shielded electrical cable 1702 is in use, e.g., when laterally oraxially bending shielded electrical cable 1702. This damage may include,e.g., fractures in conductive layer 1708 a and/or debonding betweenconductive layer 1708 a and non-conductive polymeric layer 1708 b. Inaddition, a gradual transition prevents damage to shielding films 1708in manufacturing of shielded electrical cable 1702, which may include,e.g., cracking or shearing of conductive layer 1708 a and/ornon-conductive polymeric layer 1708 b.

The configuration of shielded electrical cables according aspects of thepresent invention including a transition portion on one or both sides ofthe conductor set represents a departure from conventional cableconfigurations, such as, e.g., an ideal coaxial cable, wherein a shieldis generally continuously disposed around a single insulated conductor,or an ideal twinaxial cable, wherein a shield is generally continuouslydisposed around a pair of insulated conductors. Although these idealcable configurations provide ideal electromagnetic profiles, theseprofiles are not necessary to achieve acceptable electrical properties.In the shielded electrical cables according to aspects of the presentinvention, acceptable electrical properties can be achieved byminimizing the electrical impact of the transition portion, e.g., byminimizing the size of the transition portion and carefully controllingthe configuration of the transition portion along the length of theshielded electrical cable. Minimizing the size of the transition portionminimizes the capacitance deviation and minimizes the required spacebetween multiple conductor sets, thereby reducing the conductor setpitch and/or increasing the electrical isolation between conductor sets.Careful control of the configuration of the transition portion along thelength of the shielded electrical cable contributes to obtainingpredictable electrical behavior and consistency, which is important forhigh speed transmission lines so that electrical data can be reliablytransmitted, and becomes more important when the size of the transitionportion cannot be minimized. An electrical characteristic that is oftenconsidered is the characteristic impedance of the transmission line. Anyimpedance changes along the length of a transmission line may causepower to be reflected back to the source instead of being transmitted tothe target. Ideally, the transmission line will have no impedancevariation along its length, but, depending on the intended application,variations up to 5-10% may be acceptable. Another electricalcharacteristic that is often considered in twinaxial cables(differentially driven) is skew or unequal transmission speeds of twotransmission lines of a pair along at least a portion of their length.Skew produces conversion of the differential signal to a common modesignal that can be reflected back to the source, reduces the transmittedsignal strength, creates electromagnetic radiation, and dramaticallyincreases the bit error rate, in particular jitter. Ideally, a pair oftransmission lines will have no skew, but, depending on the intendedapplication, a differential S-parameter SCD21 or SCD12 value(representing the differential-to common mode conversion from one end ofthe transmission line to the other) of less than −25 to −30 dB up to afrequency of interest, such as, e.g., 6 GHz, may be acceptable.Alternatively, skew can be measured in the time domain and compared to arequired specification. Depending on the intended application, values ofless than about 20 picoseconds/meter (ps/m) and preferably less thanabout 10 ps/m may be acceptable.

Referring back to FIGS. 12 a-12 b, in part to help achieve acceptableelectrical properties, transition portions 1734 of shielded electricalcable 1702 may each include a cross-sectional area 1734 a that issmaller than a cross-sectional area 1706 a of conductor 1706. As bestshown in FIG. 12 b, cross-sectional area 1734 a of transition portion1734 is defined by transition points 1734′, where shielding films 1708deviate from being substantially concentric with insulated conductor1706, and transition points 1734″, where shielding films 1708 deviatefrom being substantially parallel. In addition, each cross-sectionalarea 1734 a may include a void portion 1734 b. Void portions 1734 b maybe substantially the same. Further, conformable adhesive layer 1710 mayhave a thickness T_(ac) in concentric portion 1708′, and a thickness intransition portion 1734 that is greater than thickness T_(ac) inconcentric portion 1708′. Similarly, conformable adhesive layer 1710 mayhave a thickness T_(ap) in parallel portion 1708″, and a thickness intransition portion 1734 that is greater than thickness T_(ap) inparallel portion 1708″. Conformable adhesive layer 1710 may represent atleast 25% of cross-sectional area 1734 a. The presence of conformableadhesive layer 1710 in cross-sectional area 1734 a, in particular at athickness that is greater than thickness T_(ac) or thickness T_(ap),contributes to the strength of transition portion 1734. Careful controlof the manufacturing process and the material characteristics of thevarious elements of shielded electrical cable 1702 may reduce variationsin void portion 1734 b and the thickness of conformable adhesive layer1710 in transition portion 1734, which may in turn reduce variations inthe capacitance of cross-sectional area 1734 a. Shielded electricalcable 1702 may include a transition portion 1734 positioned on one orboth sides of conductor set 1704 that includes a cross-sectional area1734 a that is substantially equal to or smaller than a cross-sectionalarea 1706 a of conductor 1706. Shielded electrical cable 1702 mayinclude a transition portion 1734 positioned on one or both sides ofconductor set 1704 that includes a cross-sectional area 1734 a that issubstantially the same along the length of conductor 1706. For example,cross-sectional area 1734 a may vary less than 50% over a length of 1 m.Shielded electrical cable 1702 may include transition portions 1734positioned on both sides of conductor set 1704 that each include across-sectional area 1734 a, wherein the sum of cross-sectional areas1734 a is substantially the same along the length of conductor 1706. Forexample, the sum of cross-sectional areas 1734 a may vary less than 50%over a length of 1 m. Shielded electrical cable 1702 may includestransition portions 1734 positioned on both sides of conductor set 1704that each include a cross-sectional area 1734 a, wherein thecross-sectional areas 1734 a are substantially the same. Shieldedelectrical cable 1702 may include transition portions 1734 positioned onboth sides of conductor set 1704, wherein the transition portions 1734are substantially identical. Insulated conductor 1706 has an insulationthickness T_(i), and transition portion 1734 may have a lateral lengthL_(t) that is less than insulation thickness T_(i). Insulated conductor1706 has a diameter D_(c), and transition portion 1734 may have alateral length L_(t) that is less than diameter D_(c). The variousconfigurations described above may provide a characteristic impedancethat remains within a desired range, such as, e.g., within 5-10% of atarget impedance value, such as, e.g., 50 Ohms, over a given length,such as, e.g., 1 m.

Factors that control the configuration of transition portion 1734 alongthe length of shielded electrical cable 1702 include the manufacturingprocess, the thickness of conductive layers 1708 a and non-conductivepolymeric layers 1708 b, conformable adhesive layer 1710, and the bondstrength between insulated conductor 1706 and shielding films 1708, toname a few.

In one aspect, conductor set 1704, shielding films 1708, and transitionportion 1734 are cooperatively configured in an impedance controllingrelationship. An impedance controlling relationship means that conductorset 1704, shielding films 1708, and transition portion 1734 arecooperatively configured to control the characteristic impedance of theshielded electrical cable.

FIGS. 13 a-13 b illustrate two other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention includingtwo insulated conductors.

Referring to FIG. 13 a, shielded electrical cable 1802 includes a singleconductor set 1804 including two substantially parallel longitudinalindividually insulated conductors 1806. Two generally parallel shieldingfilms 1808 are disposed around conductor set 1804. An optionalconformable adhesive layer 1810 is disposed between shielding films 1808and bonds shielding films 1808 to each other on both sides of conductorset 1804. Insulated conductors 1806 are arranged generally in a singleplane and effectively in a twinaxial or differential pair cablearrangement. Shielding films 1808 include a conductive layer 1808 a anda non-conductive polymeric layer 1808 b. Conductive layer 1808 a facesinsulated conductors 1806. Shielding films 1808 include concentricportions 1808′ substantially concentric with corresponding conductors1806 and parallel portions 1808″ wherein shielding films 1808 aresubstantially parallel. Shielded electrical cable 1802 includestransition portions 1834 positioned on both sides of conductor set 1804that each include a cross-sectional area 1834 a, wherein the sum ofcross-sectional areas 1834 a is substantially the same along the lengthof conductors 1806. For example, the sum of cross-sectional areas 1834 amay vary less than 50% over a length of 1 m. In addition,cross-sectional areas 1834 a are substantially the same and transitionportions 1834 are substantially identical. This configuration oftransition portions 1834 may provide a characteristic impedance for eachconductor 1806 (single-ended) and a differential impedance that bothremain within a desired range, such as, e.g., within 5-10% of a targetimpedance value over a given length, such as, e.g., 1 m. In addition,this configuration of transition portions 1834 may minimize skew of thetwo conductors 1806 along at least a portion of their length. Referringto FIG. 13 b, shielded electrical cable 1902 is similar to shieldedelectrical cable 1802. Whereas shielded electrical cable 1802 hasindividually insulated conductors 1806, shielded electrical cable 1902has jointly insulated conductors 1906. Nonetheless, transition portions1934 are identical to transition portions 1834 and provide the samebenefits to shielded electrical cable 1902.

FIGS. 14 a-14 b illustrate two other exemplary embodiments of a shieldedelectrical cable according to aspects of the present invention includingtwo insulated conductors. These exemplary embodiments are intended toillustrate variations in position and configuration of the transitionportions. Shielded electrical cables 2002 (FIGS. 14 a) and 2102 (FIG. 14b) are similar to shielded electrical cable 1802. Whereas in shieldedelectrical cable 1802, parallel portions 1808″ of shielding films 1808and insulated conductors 1806 are arranged generally in a single plane,in shielded electrical cables 2002 and 2102, parallel portions 2008″ and2108″ of shielding films 2008 and 2108 and insulated conductors 2006 and2106 are arranged in different planes. As a result, transition portions2034 and 2134 have a different position and configuration. For reasonsincluding that transition portions 2034 and 2134 are positionedsubstantially symmetrically with respect to corresponding insulatedconductors 2006 and 2106 and that the configuration of transitionportions 2034 and 2134 is carefully controlled along the length ofshielded electrical cables 2002 and 2102, shielded electrical cables2002 and 2102 are configured to still provide acceptable electricalproperties.

In further exemplary embodiments, shielded electrical cables accordingto aspects of the present invention include a plurality of spaced apartconductor sets arranged generally in a single plane. Each conductor setincludes one or more substantially parallel longitudinal insulatedconductors. Two generally parallel shielding films are disposed aroundthe conductor sets and include a plurality of concentric portionssubstantially concentric with at least one of the conductors and aplurality of parallel portions wherein the shielding films aresubstantially parallel. A plurality of transition portions defined bythe shielding films and the conductor sets provide a gradual transitionbetween the concentric portions and the parallel portions of theshielding films. The transition portions may be positioned on both sidesof each conductor set. For example, the shielded electrical cable mayinclude a combination of one or more conductor sets 1704, whereininsulated conductor 1706 is effectively arranged in a coaxial or singleended cable arrangement, and one or more conductor sets 1804, whereininsulated conductors 1806 are effectively arranged in a twinaxial ordifferential pair cable arrangement. The conductor sets, shielding filmsand transition portions may be cooperatively configured in an impedancecontrolling relationship.

The following items are exemplary embodiments of a shielded electricalcable according to aspects of the present invention.

Item 1 is a shielded electrical cable comprising a conductor setincluding one or more substantially parallel longitudinal insulatedconductors; two generally parallel shielding films disposed around theconductor set and including a concentric portion substantiallyconcentric with at least one of the conductors and a parallel portionwherein the shielding films are substantially parallel; and a transitionportion defined by the shielding films and the conductor set andproviding a gradual transition between the concentric portion and theparallel portion of the shielding films.

Item 2 is the shielded electrical cable of item 1, wherein thetransition portion includes a cross-sectional area that is substantiallyequal to or smaller than a cross-sectional area of the conductor.

Item 3 is the shielded electrical cable of item 1, wherein thetransition portion includes a cross-sectional area that is substantiallythe same along the length of the conductor.

Item 4 is the shielded electrical cable of item 1, wherein the shieldedelectrical cable includes transition portions positioned on both sidesof the conductor set.

Item 5 is the shielded electrical cable of item 4, wherein thetransition portions each include a cross-sectional area, and wherein thesum of the cross-sectional areas is substantially the same along thelength of the conductor.

Item 6 is the shielded electrical cable of item 4, wherein thetransition portions each include a cross-sectional area, and wherein thecross-sectional areas are substantially the same.

Item 7 is the shielded electrical cable of item 4, wherein thetransition portions are substantially identical.

Item 8 is the shielded electrical cable of item 4, wherein thetransition portions each include a cross-sectional area having a voidportion, and wherein the void portions are substantially the same.

Item 9 is the shielded electrical cable of item 1 further comprising aconformable adhesive layer disposed between the shielding films andbonding the shielding films to each other on both sides of the conductorset.

Item 10 is the shielded electrical cable of item 9, wherein theconformable adhesive layer has a thickness in the concentric portion,and a thickness in the transition portion that is greater than thethickness in the concentric portion.

Item 11 is the shielded electrical cable of item 9, wherein theconformable adhesive layer has a thickness in the parallel portion, anda thickness in the transition portion that is greater than the thicknessin the parallel portion.

Item 12 is the shielded electrical cable of item 9, wherein thetransition portion includes a cross-sectional area, and wherein theconformable adhesive layer represents at least 25% of thecross-sectional area.

Item 13 is the shielded electrical cable of item 1, wherein theinsulated conductor has an insulation thickness, and wherein thetransition portion has a lateral length that is less than the insulationthickness.

Item 14 is the shielded electrical cable of item 1, wherein thetransition portion has a lateral length that is less than a diameter ofthe conductor.

Item 15 is the shielded electrical cable of item 1, wherein theconductor set, shielding films and transition portion are cooperativelyconfigured in an impedance controlling relationship.

Item 16 is a shielded electrical cable comprising a plurality of spacedapart conductor sets arranged generally in a single plane, eachconductor set including one or more substantially parallel longitudinalinsulated conductors; two generally parallel shielding films disposedaround the conductor sets and including a plurality of concentricportions substantially concentric with at least one of the conductorsand a plurality of parallel portions wherein the shielding films aresubstantially parallel; and a plurality of transition portions definedby the shielding films and the conductor sets and providing a gradualtransition between the concentric portions and the parallel portions ofthe shielding films.

Item 17 is the shielded electrical cable of item 16, wherein thetransition portions are positioned on both sides of each conductor set.

Item 18 is the shielded electrical cable of item 17, wherein theconductor sets, shielding films and transition portions arecooperatively configured in an impedance controlling relationship.

Although specific embodiments have been illustrated and described hereinfor purposes of description of the preferred embodiment, it will beappreciated by those of ordinary skill in the art that a wide variety ofalternate and/or equivalent implementations calculated to achieve thesame purposes may be substituted for the specific embodiments shown anddescribed without departing from the scope of the present invention.Those with skill in the mechanical, electro-mechanical, and electricalarts will readily appreciate that the present invention may beimplemented in a very wide variety of embodiments. This application isintended to cover any adaptations or variations of the preferredembodiments discussed herein. Therefore, it is manifestly intended thatthis invention be limited only by the claims and the equivalentsthereof.

What is claimed is:
 1. A shielded electrical cable comprising: aconductor set including one or more substantially parallel longitudinalinsulated conductors; two generally parallel shielding films disposedaround the conductor set and including a concentric portionsubstantially concentric with at least one of the conductors having afirst cross-sectional area and a parallel portion wherein the shieldingfilms are substantially parallel; and a transition portion defined bythe shielding films and the conductor set and providing a gradualtransition between the concentric portion and the parallel portion ofthe shielding films, the transition portion comprising a secondcross-sectional area defined as an area between first transition pointswhere the two shielding films deviate from being substantiallyconcentric with the at least one of the conductors and second transitionpoints where the two shielding films deviate from being substantiallyparallel, the second cross-sectional area being equal to or smaller thanthe first cross-sectional area.
 2. The shielded electrical cable ofclaim 1, wherein the second cross-sectional area is smaller than thefirst cross-sectional area.
 3. The shielded electrical cable of claim 1,wherein the second cross-sectional area is substantially the same alongthe length of the conductor.
 4. The shielded electrical cable of claim1, wherein the shielded electrical cable includes transition portionspositioned on both sides of the conductor set.
 5. The shieldedelectrical cable of claim 1 further comprising a conformable adhesivelayer disposed between the shielding films and bonding the shieldingfilms to each other on both sides of the conductor set.
 6. The shieldedelectrical cable of claim 1, wherein the insulated conductor has aninsulation thickness, and wherein the transition portion has a laterallength defined as a length between the first transition points, whereinthe lateral length is less than the insulation thickness.
 7. Theshielded electrical cable of claim 1, wherein the transition portion hasa lateral length defined as a length between the first transitionpoints, wherein the lateral length is less than a diameter of theconductor.
 8. The shielded electrical cable of claim 1 comprising acharacteristic impedance that is within 5 to 10% of a target impedancevalue over a length of 1 meter.
 9. A shielded electrical cablecomprising: a plurality of spaced apart conductor sets arrangedgenerally in a single plane, each conductor set including one or moresubstantially parallel longitudinal insulated conductors; two generallyparallel shielding films disposed around the conductor sets andincluding a plurality of concentric portions substantially concentricwith at least one of the conductors having first cross-sectional areasand a plurality of parallel portions wherein the shielding films aresubstantially parallel; and a plurality of transition portions definedby the shielding films and the conductor sets and providing a gradualtransition between the concentric portions and the parallel portions ofthe shielding films, the transition portions comprising secondcross-sectional areas defined as areas between first transition pointswhere the two shielding films deviate from being substantiallyconcentric with the at least one of the conductors and second transitionpoints where the two shielding films deviate from being substantiallyparallel, the second cross-sectional areas being equal to or smallerthan the first cross-sectional areas.
 10. The shielded electrical cableof claim 9, wherein the transition portions are positioned on both sidesof each conductor set.